Let s say your solar panels battery bank produced 7 amps and you were using a wire length of 4 6m.
Using low voltage wire for solar panels.
Sorry for the late response was at scout camp the last week.
No quick and easy way to do it.
You can place a solar panel where it gets light for power and run the cable to the fixtures.
When solar panels are wired in series the voltage of the panels adds together but the amperage remains the same.
With solid wire you can not get the intimate contact between two wires nor at the connections on a device switch etc or load.
Some exceptions may apply based on panel type.
This is starting to get lengthy so add a 35 safety margin which is.
4 awg will handle 90 amps and at 24 volts that s more than 2000 watts.
Use these numbers for a 12 volt system to achieve a 3 or less voltage drop.
7 35 of 7 9 45 amps.
Below is a chart showing the required wire size for wire lengths to connect the solar panels to the charge controller.
My preference is to use stranded wire in a low voltage system.
The top row represents the wire gauge size the left column the number of amps the solar panels are rated at and the grid cells show the distances in feet between the solar panels and the charge controller.
You need to understand how different stringing configurations impact the voltage current and power of a solar array.
It is somewhat like low voltage lights without having to have a need for a 110 volt power source.
Therefore you would need 10 amp wire.
Follow that line across to the right to find your wire length in feet from solar to batteries.
Wire size tables for low voltage find wire size required for less than 5 power loss read down the left hand edge to the number showing solar amps or watts your wire will carry for off grid power.
Simply touch the solar panel leads with the multi meter probes matching their corresponding polarity red to red black to black.
Open circuit voltage can vary depending on your solar panel but the readings we are usually looking for are in the range of 15 to 23v.
With stranded wire you get more intimate contact thus reducing.
Know the maximum expected current and size the wire then check against a v drop calculator over the distance to see how much you suffer.